Measurement Probe

Measurement Probe

(MPROBE) Measurement probe (RED) with reference to measurement probe (BLACK).

Switched Power Input

(POWIN+) A/CCM Pin 44 ref Pin 6
Switched power-in is a signal from the control module. Unlike the unswitched power available on pins 1 and 12, this signal is only available when the A/C is switched on.

Power Output

(POWOP+) A/CCM Pin 12 ref vehicle battery +ve
This is the ignition power for the whole A/C system. It passes through the A/CCM via pins 1 and 12 (and a feedback protection diode) before supplying the fan control switch. Pin 12 should normally read battery voltage with the ignition switch in positions I or II. With the ignition switch off, pin 12 should read 0 volts.

Right Blower Feedback Voltage

(RBLOFB) A/CCM Pin 33 ref Pin 6
The purpose of the blower feedback is to inform the control module of the present blower speed. This enables the control module to directly monitor and control blower motor speed. With Manual selected, the blower operates in four basic ranges:

• Low Speed
  Temp Min: pin 33 = 5±1 volt
  Temp Med: pin 33 = 9±1 volt
  Temp Max: pin 33 = 5±1 volt
• Medium Speed
  Temp Min: pin 33 = 2±1 volt
  Temp Med: pin 33 = 6±1 volt
  Temp Max: pin 33 = 2±1 volt
• High Speed
  Pin 33 = 1±1 volt at all temperature settings
• Defrost
  Pin 33 = 1±1 volt at all temperature settings

Right Blower Output Voltage

(RBLOWOP) A/CCM Pin 32 ref Pin 6
This signal is produced by the control module to drive the blower motor. The signal can vary from 0-3 volts depending on blower motor speed. The higher the voltage, the higher the blower motor speed. This signal is amplified by a simple amplifier circuit inside the blower motor. This circuit also supplies the feedback signals to pins 22 and 33.

Note: If the signal rises above 5 volts, then suspect a fault in the amplifier circuit.